E-health is the use of ICT to improve the ability to treat patients, facilitate behavior change, and improve health. It has many benefits like healthcare cost reduction, convenience for users, and health system improvement. Several literature reviews have included one part or the other of the field, but an overall review is lacking possibly due to the field's constant evolution. An overview of E-health research is needed. We selected the related literature on E-health downloaded from Web of Science and PubMed as data source and used the visualization analysis function of CiteSpace. Literature information would be converted into precise mapping knowledge domain. Through further analysis of mappings, we explored the theoretical framework and the forefront in the field of E-health. Our study shows that over the past 15 years, the USA, England, and Australia were the top three countries that published the largest number of papers. Researches about Internet technology, telemedicine (m-health), and healthcare lay the basis of Ehealth research development. Particularly, m-health, health system management, and experimental intervention have emerged and formed the new study frontier in the recent 3-5 years. With the advancement of E-health projects, an increasing number of scholars have been studying the commercialization of E-health.